This invention relates to railway car couplers and, in particular, to an improved thrower arm utilized to open the knuckle of the coupler.
In knuckle-type couplers, such as the Association of American Railroad's standard F coupler, the knuckle is swung open by means of a horizontaly positioned knuckle thrower which is mounted for rotation about a vertical axis and which has an arm that bears against a pad on the knuckle in response to actuation of an uncoupling mechanism. As the knuckle thrower rotates, the force exerted by the end of the thrower arm against the knuckle pad pivots the knuckle about its pivot pin to the open position.
Frequently there is difficulty in throwing open the knuckle of existing couplers. This is due, at least in part, to service wear between certain parts of the knuckle and coupler head which heretofore has impeded such opening.
There have been earlier attempts in the coupler art to solve the same problem. One such earlier attempt involved changing the angle of the knuckle thrower pad in an attempt to make opening the knuckle easier. Another earlier prior art arrangement involved in a redesigned lock in an attempt to solve the same problem. Still further attempts have been made to solve the problem by changing the shape and relationship of the arm of the knuckle thrower engaging the lock, the lock, and the lifter. None of the prior art arrangements have been totally satisfactory.
In particular, none of the prior art arrangements prevent the occurrence of the thrower jamming in the concave surface joining the knuckle thrower pad to the main body of the knuckle under worn conditions. In severe jamming cases, fracture of the thrower has resulted. During operation of the standard thrower, the force exerted on the knuckle pad pulls the knuckle buffing shoulders against the coupler buffing shoulders when the clearance therebetween has been diminished due to rust or damage and/or wear of the pin protector lugs. The resultant jamming of the respective shoulders causes high resistance to opening the knuckle.
Currently, when such high resistance to knuckle opening occurs, excessive force must be applied to the knuckle opening mechanism to achieve knuckle opening. In severe cases, even the application of excessive force is not sufficient to achieve knuckle opening. In such cases, the knuckle must be manually moved by an operator.